Does L-tryptophan Have Any Side Effects ? This Article Will Tell You

L-tryptophan is an essential amino acid that plays a crucial role in the synthesis of serotonin and melatonin, both of which are important neurotransmitters in the brain. It is commonly found in various foods and is also available as a dietary supplement. While L-tryptophan is generally safe for most people when taken within recommended doses, there can be potential side effects and interactions to be aware of:

Gastrointestinal Issues:

Some people may experience digestive problems when taking L-tryptophan supplements. This can include nausea, diarrhea, or stomach discomfort.

Allergic Reactions:

Although rare, allergic reactions to L-tryptophan supplements can occur. Symptoms may include itching, hives, swelling, and difficulty breathing. If you experience these symptoms, seek immediate medical attention.

Sedation or Drowsiness:

L-tryptophan is a precursor to serotonin, which can be converted to melatonin, a hormone that regulates sleep. As a result, some people may feel drowsy or experience increased sleepiness when taking L-tryptophan supplements. It’s often used as a sleep aid for this reason, but it should not be taken before activities that require alertness.

Serotonin Syndrome:

L-tryptophan can interact with certain medications that affect serotonin levels, such as selective serotonin reuptake inhibitors (SSRIs) and monoamine oxidase inhibitors (MAOIs). Combining L-tryptophan with these medications can lead to a potentially dangerous condition called serotonin syndrome, which can include symptoms like agitation, rapid heart rate, and high blood pressure. It’s important to consult with a healthcare professional if you are taking any of these medications.

Eosinophilia-Myalgia Syndrome (EMS):

In the late 1980s, a batch of L-tryptophan supplements was linked to an outbreak of EMS, a rare and severe condition that involves muscle pain, weakness, and skin rashes. The cause of this outbreak was traced to contamination in a specific batch of L-tryptophan supplements. As a result, the sale of L-tryptophan was banned in the United States for several years. Today, L-tryptophan supplements are generally considered safe, but it’s crucial to purchase from reputable sources.


L-tryptophan may interact with other medications or supplements. It’s essential to consult with a healthcare provider before taking L-tryptophan if you are on any prescription medications or have existing medical conditions.

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